Relationship between electrogenic performance and physiological change of four wetland plants in constructed wetland-microbial fuel cells during non-growing seasons

To find suitable wetland plants for constructed wetland-microbial fuel cells(CW-MFCs),four commonly used wetland plants, including Canna indica, Cyperus alternifolius L., Acorus calamus, and Arundo donax, were investigated for their electrogenic performance and physiological changes during non-growing seasons. The maximum power output of12.82 mW/m~2 was achieved in the A. donax CW-MFC only when root exudates were being released. The results also showed that use of an additional carbon source could remarkably improve the performance of electricity generation in the C. indica and A. donax CW-MFCs at relatively low temperatures(2–15°C). However, A. calamus withered before the end of the experiment, whereas the other three plants survived the winter safely, although their relative growth rate values and the maximum quantum yield of PSII(Fv/Fm) significantly declined, and free proline and malondialdehyde significantly accumulated in their leaves.On the basis of correlation analysis, temperature had a greater effect on plant physiology than voltage. The results offer a valuable reference for plant selection for CW-MFCs.     

Modeling individual and population dynamics in a consumer–resource system: Behavior under food limitation and crowding and the effect on population cycling in Daphnia

In population modeling, a considerable level of complexity is often required to provide trustworthy results, comparable with field observations. By assuring sufficient detail at the individual level while preserving the potential to explore the consequences at higher levels, individual-based modeling may thus provide a useful tool to investigate dynamics at different levels of organization. Still, population dynamics resulting from such models are often at odds with observations from the field. This may be partly caused by a lack of focus on the individual dynamics under conditions of food stress and starvation. I developed a physiologically structured, individual-based simulation model to investigate life history of Daphnia and its effect on population dynamics in response to the productivity of the system. In verifying model behavior with available literature data on life history and physiology, I paid special attention to the dynamics of food intake and the verification of individual level results under conditions of food limitation and starvation. I show that the maximum filtering rates under low food levels used in the current model are much closer to measured filtering rates than the ones used in other models. Being consistent with results on physiology and life history from experiments at a wide range of food availability (including starvation), the model generates low amplitude or high amplitude population density cycles depending on the productivity of the system, as observed in field and experimental populations of Daphnia and with the minimum population densities being one to two orders of magnitude lower in the high amplitude than in the low amplitude cycles. To generate results which are not only qualitatively but also quantitatively comparable to experimental and field observations, however, a crowding effect on the filtering response has to be incorporated in the model.     

Microbial indicators of heavy metal contamination in urban and rural soils

Urban soils and especially their microbiology have been a neglected area of study. In this paper, we report on microbial properties of urban soils compared to rural soils of similar lithogenic origin in the vicinity of Aberdeen city. Significant differences in basal respiration rates, microbial biomass and ecophysiological parameters were found in urban soils compared to rural soils. Analysis of community level physiological profiles (CLPP) of micro-organisms showed they consumed C sources faster in urban soils to maintain the same level activity as those in rural soils. Cu, Pb, Zn and Ni were the principal elements that had accumulated in urban soils compared with their rural counterparts with Pb being the most significant metal to distinguish urban soils from rural soils. Sequential extraction showed the final residue after extraction was normally the highest proportion except for Pb, for which the hydroxylamine-hydrochloride extractable Pb was the largest part. Acetic acid extractable fraction of Cd, Cu, Ni, Pb and Zn were higher in urban soils and aqua regia extractable fraction were lower suggesting an elevated availability of heavy metals in urban soils. Correlation analyses between different microbial indicators (basal respiration, biomass-C, and sole C source tests) and heavy metal fractions indicated that basal respiration was negatively correlated with soil Cd, Cu, Ni and Zn inputs while soil microbial biomass was only significantly correlated with Pb. However, both exchangeable and iron- and manganese-bound Ni fractions were mostly responsible for shift of the soil microbial community level physiological profiles (sole C source tests). These data suggest soil microbial indicators can be useful indicators of pollutant heavy metal stress on the health of urban soils.     

紫茎泽兰与伴生植物小藜的竞争效应及其生理生化特征

外来入侵物种紫茎泽兰（Ageratina adenophora Sprengel）是一种世界性入侵杂草,其与本地物种的竞争会对生态系统结构和演替造成严重影响,带来较大经济损失;拟通过分析紫茎泽兰与本地物种小藜的竞争效应及生理生化特征,以探讨外来入侵物种紫茎泽兰的竞争机理。在温室条件下,设置紫茎泽兰、小藜（Chenopodium serotinum）的种内和种间竞争盆栽试验,测定了两种植物不同处理下的植株生物量;并通过氮蓝四唑光化还原法、紫外吸收法、三氯乙酸法和酸性茚三酮法,分别测定了功能叶片的超氧化物歧化酶活性、过氧化氢酶活性、丙二醛含量、脯氨酸含量。结果表明：紫茎泽兰与小藜混种时,紫茎泽兰的单株生物量、相对产量（RY）均显著高于小藜对应指标,其竞争平衡指数（CB）显著大于0,而相对产量总和（RYT）显著小于1。混种与单种的结果比较表明,紫茎泽兰的混种生物量比在单种时显著增高,增幅达22.01%;而小藜的混种生物量比在单种时显著降低,降低了44.81%。在混种中,紫茎泽兰功能叶片的丙二醛、脯氨酸含量均比在单种时显著降低,而超氧化物歧化酶、过氧化氢酶活性均比在单种时显著升高;小藜功能叶片的丙二醛含量显著高于单种,而脯氨酸含量、超氧化物歧化酶活性、过氧化氢酶活性与单种无显著变化。这说明紫茎泽兰的相对竞争能力比小藜强,紫茎泽兰通过调整生理生化特征来应对种间竞争可能是其竞争取胜的重要策略。     

Response of mussel Brachidontes variabilis to chlorination

Brachidontes variabilis is a common fouling mussel species in cooling water systems of tropical coastal power stations. However, there are hardly any data available on the response of B. variabilis to chlorine, a commonly used antifouling biocide. Therefore, lethal and sublethal responses of this mussel to chlorine are of considerable interest to the industry. The response of mussels in terms of mortality pattern (LT₅₀ and LT₁₀₀) and physiological activities (oxygen consumption, filtration rate, foot activity and byssus thread production) in different size groups (with shell lengths of 7–24 mm) of B. variabilis was studied in the laboratory under different chlorine concentrations (0.25, 0.50, 0.75 and 1.00 mg l^?1 for sublethal responses and 1, 2, 3 and 5 mg l^?1 for mortality). The results showed that the exposure time for 100% mortality of mussels decreased significantly with increasing chlorine concentration. However, mussel size was not a determinant of its chlorine tolerance: all size groups tested (with shell lengths of 7–24 mm) took comparable exposure times to reach 100% mortality at a given chlorine concentration (1–5 mg l^?1). All size groups of B. variabilis showed a progressive reduction in physiological activities such as oxygen consumption, filtration rate, foot activity and byssus thread production, when chlorine residuals were increased from 0 to 1 mg l^?1. The data generated in the present work are compared with similar data available for other tropical fouling mussel species to see how far relative chlorine toxicity could have influenced the relative distribution of the mussels inside the seawater intake tunnel of a power station at Kalpakkam in India. It is shown that in this insufficiently chlorinated system, the relative distribution of Brachidontes striatulus, B. variabilis and Modiolus philippinarum reflects the relative tolerance of the species to chlorine.     

不同光环境下薇甘菊形态和生理可塑性及其响应研究

研究了华南地区外来入侵种薇甘菊Mikania micrantha H B Kunth不同光环境下形态和生理可塑性及其适应性响应。通过模拟开阔地段、林缘、大林窗、小林窗、林下等不同生境的的光照环境,并设计一个干扰实验,分析了薇甘菊的生长、碳同化以及生物量分配如何对光环境作出适应性响应。研究了当干扰发生时,薇甘菊如何对光环境的变化做出形态和生理可塑性响应。通过对其各项生物量分配及气体交换等指标的观测,在小林窗光照环境下薇甘菊生长缓慢生物量积累较少,但是如果一旦受到干扰,光照环境得到改善,薇甘菊将在很短的时间内通过适应性形态和生理可塑性响应,迅速体现出较强的入侵性。这也可能是入侵植物薇甘菊＂坐待对策（sit and wait strategy）＂的生动体现：如果外界环境不利,暂且先保持繁殖体（种子或者根茎）,一旦条件成熟（发生干扰条件得到改善或者遗传变异或者生态生理的积累）,就会迅速爆发。所以我们一方面,不用担心郁闭的森林会被薇甘菊入侵,但另一方面也要注意干扰会引起光照等环境条件的改变,使得原来潜伏于林下的薇甘菊繁殖体重新变得富有入侵性。     

Research progress and prospects of complete ammonia oxidizing bacteria in wastewater treatment

• Comammox bacteria have unique physiological characteristics. • Comammox bacteria are widely distributed in natural and artificial systems. • Comammox bacteria have the potential to reduce N₂O emissions. • Coupling comammox bacteria with DEAMOX can be promoted in wastewater treatment. • Comammox bacteria have significant potential for enhancing total nitrogen removal. Complete ammonia oxidizing bacteria, or comammox bacteria (CAOB), can oxidize ammonium to nitrate on its own. Its discovery revolutionized our understanding of biological nitrification, and its distribution in both natural and artificial systems has enabled a reevaluation of the relative contribution of microorganisms to the nitrogen cycle. Its wide distribution, adaptation to oligotrophic medium, and diverse metabolic pathways, means extensive research on CAOB and its application in water treatment can be promoted. Furthermore, the energy-saving characteristics of high oxygen affinity and low sludge production may also become frontier directions for wastewater treatment. This paper provides an overview of the discovery and environmental distribution of CAOB, as well as the physiological characteristics of the microorganisms, such as nutrient medium, environmental factors, enzymes, and metabolism, focusing on future research and the application of CAOB in wastewater treatment. Further research should be carried out on the physiological characteristics of CAOB, to analyze its ecological niche and impact factors, and explore its application potential in wastewater treatment nitrogen cycle improvement.     

Cd对桐花树幼苗生长及某些生理特性的影响

通过砂培实验研究了红树植物桐花树幼苗在含Cd0.05-100μg/L系列海水培养液（盐度为10）中的生长及某些生理特性的变化。当培养液中Cd浓度低于0．5μg/L时，随Cd浓度的增加，桐花树幼苗的生长加快，叶片叶绿素含量，过氧化物酶（POD）和超氧化物酶（SOD）活性均有所提高，而抽条水势则略有下降。而当高于0.5μg/L时，桐花树幼苗的生长减缓，叶片叶绿素含量，过氧化物酶（POD）和超氧化物酶（SOD）活性均出现不同程度的下降，抽条水势则迅速升高。不同Cd浓度下，桐花树叶片的细胞膜透性变化不大，但膜脂过氧化作用随着Cd浓度的增加而不断增强。红树植物桐花树对Cd金属有较强的耐性。